Sealant for pneumatic tires

ABSTRACT

A self-sealing lining is provided in pneumatic tires which includes an aqueous blend of a blocking agent, a binding agent, an adhesive agent and a diluent.

O Unlted States Patent 1151 3,676,381 Silverstein 451 July 1 1, 1972 s41SEALANT FOR PNEUMATIC TIRES 2,336,065 12/1943 Cadham 102/42 2,419,6144/1947 Welch r ..20/89 [72] Inventor: Joseph J. Silver-stein, Woodmere,NY. 2,433,349 H1943 Lathrop et aL 106/122 73 A I E 2,506,309 5/1950Middleman ...260/17 3 1 Sslgnee sine Power College N 2,806,008 9/1957McNulty et a1 ..260/1 7.4 [22] Filed: Feb. 18, 1969 PrimaryExaminer-Melvin Goldstein [21] Appl' 800354 Attorney-Brenner,OBrien,Guayand Connors 52 US. (:1. ..260/17.4 R, 260/l7.4 CL, 260/17.4 so [57]ABSTRACT [51] Int. Cl. ..C08l 41/06, C081 37/00 A self-sealing lining isprovided in pneumatic tires which in- [58] Field of Search ..260/l7.4 R,17.4 ST, 17.4 $6 cludes an aqueous blend ofa blocking agent, a bindingagent,

an adhesive agent and a diluent. [5 6] References Cited UNITED STATESPATENTS Crowley 106/22 2 Claims, No Drawings SEALANT ros PNEUMATIC TIRESBACKGROUND OF THE INVENTION This invention relates to self-sealinglinings which can be used in rubberized containers. More particularly,this invention relates to self-sealing linings for pneumatic tires,tubes and the like. In another aspect, this invention relates to animproved method for sealing a puncture in a pneumatic tire.

Punctured inner tubes, and more recently, tubeless tires, have in thepast been repaired by applying a rubberized patch to the damaged area.Such a repair process requires careful and skillful manipulations inapplying the patch for satisfactory repair and the avoidance ofsubsequent partial or complete detachment of the patch. Moreover, in allpatch repairs which areeffected on resilient, hollow, pneumatic,containers, such as a motor vehicle tire, it is important that thepatches be so positioned in the damaged area, for example a hole orpuncture caused by the penetration of a nail or spike, that the thickestand strongest part of the main body of the patch be disposed over theactual damaged area. This is necessary to avoid excessive stress aboutthe edge portions of the patch, made thin for specific reasons, andoverstretching andin certain instances damage or detachment particularlyunder conditions involving considerable pressure such as, for example,the high pressures existing inside the inner tube of a heavy truck tire.Experience has demonstrated that even when all prescribed conditions arefollowed, overstressing of the patch frequently occurs, particularlywhen the patches are used to repair motor vehicle inner tubes. This isespecially noticeable when the patch is applied at portions of the tubewhich when subsequently inserted in the tire casing are not subjected tocounteracting pressures ,or are only subjected to slight pressure due tocontact.

Accordingly, the present invention has for an object provision ofself-sealing linings for pneumatic tires, tubes and the like whichobviates the above disadvantages inherent in patching techniques andsolves the problem therein of establishing a favorable compensation oftension between the middle portion of a patch, the edge of a patch, andthe article being repaired.

Other objects and advantages of the instant invention as compared withprior art will become more apparent upon examination of the followingmore detailed disclosure' SUMMARY OF THE INVENTION According to theinstant invention, inner tubes and tubeless tires can be provided with aself-sealing lining, which lining tends to How into punctures or breaksin the wall or crown of the tire thereby preventing the escape of air.Tire puncture sealants of the instant invention are maintainedsufficiently fluid, at all times, to flow around a penetrating objectand follow the object into the puncture as the object, such as a nail orspike, is removed. This sealant material maintains its integrity andfluidity under all road conditions, including the higher temperaturesencountered in summer driving. Furthermore, tire puncture sealants ofthe instant invention, when incorporated in a tire or tire tube, form asubstantially uniform coating therein of fluid, tacky, sealing materialthat resists agglomeration while the tire is at rest for long periods oftime and in an unpunctured condition.

Puncture sealants of the instant invention are incorporated in varioustypes of inflatable rubber-lined objects by injectinG the sealantcomposition into said objects while in a deflated condition. Immediatelyafter the sealant composition is injected into a rubber object, theobject can be inflated to assume a functional posture. Althoughself-sealing linings of this invention can be applied to various typesof inflatable rubber lined objects, their greatest advantages are in theapplication to pneumatic inner tubes and tubeless tires. The process ofequipping pneumatic inner tubes and tubeless tire with the selfsealinglinings of this invention comprises removing the valve assembly from thepneumatic inner tube or tubeless tire and deflating said tube ortubeless tire, injecting the sealant composition through the valvehousing, replacing said valve assembly in said value housing, andinflating said pneumatic inner tube or tubeless tire for immediate use.Sufficient sealant composition is injected into the tube or tubelesstire to substantially coat the interior surface thereof, usually abouteight ounces of said sealant composition is preferred.

The sealant compositions of use in the instant invention comprise incombination a blocking agent, a binding agent, an adhesive, and adiluent, mixed together in an aqueous blend.

DESCRIPTION OF PREFERRED EMBODIMENT The blocking agent used in theinstant composition is a mixture of wood chips and shredded paper. Thewood chips, preferably of soft pine, must be less than mesh, preferablyabout mesh, while the shredded paper must be of a width lessthree-sixteenths inch, preferably about one-eighth inch.

The binding agent is an aqueous acrylic copolymer emulsion. Monomerwhich may be employed in the preparation of suitable copolymer includecompounds such as butyl acrylate,

ethyl acrylate, methyl methacrylate, methacrylic acid, styrene and vinylacetate. A preferred acrylic copolymer is that obtained copolymerizingbutyl acrylate, styrene and methacrylic acid; a more preferred acryliccopolymer is that obtained by copolymerizing ethYl acrylate, methylmethacrylate and vinyl acetate. Emulsions of these acrylic copolymersare formed by dispersing the resin in an aqueous system using suitablesurface active agents or emulsifiers. Anionic emulsifiers may beemployed for this purpose but it has been found that mixtures of anionicand nonionic emulsifiers are preferred to obtain optimum particle sizeand ease of reaction. Suitable emulsifiers in the instant inventioninclude sodium dioctyl sulfosuccinate, nonylphenoxypoly(oxyethylene)-ethanol, etc. A feature of these aqueous emulsions is thatthey remain fluid and tacky at tire temperatures encountered undernormal highway operating conditions, for example temperatures within therange of l40-l60 F.

When the pneumatic tire or tube is punctured, the binding agent andblocking agent cooperate to form an airtight seal over the damaged area.An adhesive agent is employed to firmly secure this seal to the rubberwall of said pneumatic tire or tube. It is, therefore, required thatthis adhesive be compatible with rubber and the binding agent. Asuitable adhesive agent is found to be corn syrup.

The diluent employed in the instant invention acts as a carrier for thebinding agent and causes said binding to retain its tacky consistency.Ethylene glycol is a preferred diluent and operates to maintain thebinding agent in the necessary fluid and tacky state when the sealantcomposition is maintained in a closed container, for example, aninflated tire.

The following examples are provided to illustrate the instant inventionmore fully. They are provided for illustrative purposes only and are notto be construed as limiting the invention, which is defined by theappended claims. In the examples, all parts are by weight unlessindicated to the contrary.

EXAMPLE I A sealant composition is prepared by admixing 950 parts of a40 percent aqueous emulsion of ethyl acrylate-methyl methacrylate-vinylacetate copolymer (commercially available from Emulsion Systems, Inc.under the trade name "Esicryl 0600"), 330 parts of lOO mesh soft pinewood chips, 15 parts shredded paper of /s-inch width, 300 parts of cornsyrup, 600 parts of ethylene glycol, and 2,635 parts of water. Eightounces of this sealant composition are injected into a deflatedpneumatic tire, from which the valve assembly has been removed, throughthe valve housing aperture. The valve assembly is immediately replacedin its housing and the tire inflated to 30 pounds pressure.

The inflated tire is mounted on an automobile which is then driven athighway speed to develop normal tire operating temperature. The tire isthen driven over and punctured by a Vsinch diameter nail. A seal isformed by the injected composition and the tire does not becomedeflated.

EXAMPLE [I A sealant composition is prepared as in Example I wherein acopolymer consisting of 60 parts butyl acrylate, 35 parts styrene and 5parts methacrylate is substituted for said ethyl acrylate-methylmethacrylate-vinyl acetate copolymer. The composition is employed in apneumatic tire in the manner illustrated in Example I and similarresults are obtained thereby.

The composition of the above copolymer may be varied within thefollowing range: butyl acrylate, 45-70 percent; styrene, 24-53 percent;methacrylic acid, 2-6 percent.

lclaim:

l. A self-sealing composition which resists agglomeration and remainsfluid and tacky at temperatures of 140 to 160 F., which compositioncomprises by weight an aqueous blend of a blocking agent comprisingabout 330 parts of 100 mesh soft pine wood chips and about parts ofshredded paper of about Va-inch width; about 950 parts of a bindingagent, comprising an aqueous emulsion containing about 40 percentsolids, said solids being an ethyl acrylate-methyl methacrylatevinylacetate copolymer; about 300 parts of adhesive comprising corn syrup;about 600 parts of diluent comprising ethylene glycol; and about 2,635parts water.

2. A self-sealing composition which resists agglomeration and remainsfluid and tacky at temperatures of to E, which composition comprises byweight an aqueous blend of a blocking agent comprising about 330 partsof 100 mesh soft pine wood chips and about 15 parts of shredded paper ofabout xiz-inch width; about 950 parts of a binding agent, comprising anaqueous emulsion containing about 40 percent solids, said solids being abutyl acrylate-styrene-methacrylic acid copolymer; about 300 parts ofadhesive comprising corn syrup; about 600 parts of diluent comprisingethylene glycol; and about 2,635 parts water.

2. A self-sealing composition which resists agglomeration and remainsfluid and tacky at temperatures of 140* to 160* F., which compositioncomprises by weight an aqueous blend of a blocking agent comprisingabout 330 parts of 100 mesh soft pine wood chips and about 15 parts ofshredded paper of about 1/8 -inch width; about 950 parts of a bindingagent, comprising an aqueous emulsion containing about 40 percentsolids, said solids being a butyl acrylate-styrene-methacrylic acidcopolymer; about 300 parts of adhesive comprising corn syrup; about 600parts of diluent comprising ethylene glycol; and about 2,635 partswater.